Propaganda (3) – Why not?

So, now suppose that we have convinced ourselves that there is a real difference between propaganda and argument along the lines outlined in propaganda (2). The question now becomes: is there any reason to refrain from using anything that would fall into the category of propaganda? For clarity, let’s take a case where what you are trying to get your audience to do is not in itself evil. You don’t try to get them to kill somebody, but to put up solar panels, for example.

Propaganda can certainly be effective in influencing your audience, so it does not seem imprudent to use it. If you are a Kantian, you can reject it on moral grounds, because you are presumably not sufficiently respecting a person’s humanity when you are trying to manipulate them. But what about the non-Kantians? Is there a good reason not to use propaganda for them?